This laboratory has been involved in contributing to the development of a malarial vaccine. To this end we have been characterizing surface antigen genes from Plasmodium falciparum. We have found that variation in the circumsporozoite gene of P. falciparum is likely to be biologically selected because of interaction of the parasite surface molecule wiith host T-cells. We have also studiied the ribosomal RNA of different malarial parasites. Information from these studies has imporatant ramifications for the development of malaria diagnostics, the understanding of evolutionary relationships among the defferent malarial species and the understanding of coontrol of the parasites developomental cycle.